M. A. H., of N. Y.—You cannot get a patent for the eccentric on the main shaft attached to a pitman ; it is a common device applied to pumps, stampers, c, and is common property to apply to any machine for the same purpose A chimney on a height will give the best draft. A brick flue is better than a pipe of metal in its nature, but it is not of such a good form inside for the draught. m E. W ,'of N. Y.—Your example about the ball requires to be more carefully repeated. The earth travels in itscurved orbit just as far in 24 hours as it would do in a straight line. A. R,, ofN. C,—In the discharge of a cannon, the elasticity of the gases suddenly liberated by the ignited powder, acts equally in all directions. A B. M,, of Texas.—Cast-iron cranes should not be loaded with more than one-tenth of the weight that will break them, and when they are intended to lower heavy bodies by means of brakes, their load should not be more than one-twentieth of the breaking weight. A, R., of N. H.—The essential principles of statics and dynamics apply equally to fluids anil solids. W. M , of Mo.—The intensity of the magnetic force is greatest at the poles, and diminishes towards the equator. A., of The statistics of the P. 0. Department would be very usef u.1 if printed on the envelopes, but it never would answer to ask for the names of the different places of our country to be printed en them —it would not pay. J, M. P. 3 of Tenn,—We should not wish to undertake your case after its passage through other hands, as no doubt your agent will do the best he can for you. You could not patent the wheel. L. K., of N. Y.—We recommend you to obtain Mini fie'8 Mechanical Drawing Book, price $3. R. B, W, of N. C— We do not know of any submarine examiner for sale, Willard Day, of Brooklyn, N, Y , is the patentee of an apparatus for the purpose, and might furnish you with. one. G. W. C, of Pa.—We think your improvement in constructing Ere places and flues is new and patent-able at least we do not remember to have seen any thing like it. W. D,, Jr., of Pa.—There are some things about your rotary engine which, are new to us, but we cannot see what advantage you gain over the one illustrated in No. 18, Vol. 4, Sci. Am. J. Y S, of Pa.—We have never known of a cider mill embracing the improvement described in yours of the 11th inst, but it is quite common in oil presses. We have seen them so constructed, therefore you could not obtain a patent for its application to a new purpose. 3. A., of Mass.—Minnifie's Mechanical Drawing Book treats upon all branches of the art. The price of the book including pre-payment of postage is $3,50. We can give no information in regard to the rule. We have placed the $1 to your credit for an additional six months subscription. J. D. B., of Ala.—There are no good low priced works upon architecture. The American House Carpenter is useful and is sold for about $2. I. W M., of Tt—The form of the lathe could not be secured by a patent, the machine could, in our opinion, be secured. The Alcott lathe is a good one, we know of none better, but cannot advise you respecting the market for handles here. N. A.j ofNe.—Wehavenodoubtof the success of your invention when fairly brought out. The cause of its failure is doubtless owing to defective workmanship. The latter is important to the success of every mechanic. H. B. G., of 111.—We are not able to give you the required information about th,e " grits". The paper will be sent to your address regularly. It has been directed to the wroDg State. R. T., ofPhila.— Your measuring apparatus appears to be very simple, but we cannot undertake to furnish you with a party who would engage in their manufacture. This object might be accomplished by an advertisement. A, S. A,, of Conn.—You could not patent the application of any well-known method to a new purpose. It is not regarded as an invention. An in-veutionmay be publicly used two years before making an application for a patent, but it is not always safe to take advantage of this provision in the law. J. C. S., of N.Y.—We do not as yet understand the manner in which examinations will be conducted under Mr. Ray's prizes. We suppose the investigations will be conducted a week at least before the close of the exhibition. C. F. 0., of Mass.—If your methodof disconnecting car wheels from axles while turning curves would be useful providing it does not increase the liability of throwing the cars off the track. Your suggestions aie quite new to us in regard to connecting and dis connecting the wheel. If it has ever been tried we have no knowledge of the fact. Submit the matter to an experimental test, this is the only and surest way. J. D. R., ofPhila.—We will attend to your communication next week A. R,, ofN Y.—You may depend upon it, the coke brick is all moonshine, so far as cheapness is concerned. Common clay brick can be rendered water-proof in the same manner. The extract in the Post must i be taken from a foreign journal. C. B, Q-., of Conn.—We do not remember to have seen a carpenter's bevel constructed in the manner shown in your communication. If it is useful a patent might be granted for it. It is a very difficult point to decide what view the Commissioner of Patents might take of it. R. S. B., of Col. H.—If we published your letter you would regret it; you will find that ice contains 140 deg. of latent heat, the trade winds are not caused by the rotation of the earth on its axis; and the telescope has a 13 feet aperture; all these statements are facts, and you would not like to see authorities quoted to make people smile at the corrector beiDg corrected for his want of correct information. L. A. S., of N. Y.—We seat your note to Mr. Wells, He is a millwright and can doubtless furnish you. S. C. K., of Wis.—Your favor of the 6th inst. covering 15 came safe to hand Gillespies work on road making is the best one we know of. A. S, Barnes Co., 51 John street, N. YM publishers. Price about $2. J. S, ofN. Y.—You are mistaken about the tin pipes, they are not so good for radiating heat as those made of iron. We could not advise you to use 10 inch tin pipe upon any consideration. You are right about .the collapse, if a vacuum is allowed to be formed in such tubes ; this can be prevented by having a light valve openiDg inwards. S- S., of S. C—We have referred your letter to a manufacturer for attention. W. L. B., of Pa.—Your proper course will be to visit large agricultaral warehouses like A. B. Allen Co., or John Mayer Co., of this city. It would give us considerable trouble to furnish a list as complete as you would require. F. S. 0,, of Mass.—We regard your" boiler arrangement as a novel contrivance, and have no doubt of its patentability. You will need to test its working capabilities. The two other devices we cannot regard as patentable. Z. B., of N. Y.—You are right about the decision of the judge respcting the height of a smoke pipe on the Ohio river boats, but the height is an entirely different question from the length. The spiral pipe would increase the evil; the shorter the horizontal flue the better, and the higher the chimney the better. The philosophical reasons were set forth in our last volume while discussing this case. Money received on account of Patent Office business for the week ending Saturday Oct. 16 :— N. C, of Ct, $10: A. 0., of N. Y.. $50; S. B., of Ind., $30 ; J. E,, of R. I., $15 ; R. S., of N. J., $30 : W. C, of Ct.. $30; E. Van. C, of Pa., $25; Q P., of N. Y., $20; S. K., of Pa., $20; J. D. C, of N. Y, $25; T. ftt, of Pa., $50; H. F P,,of N Y., $7; J. E. W., of Pa, $30; N.G. N., o'f Mass., $30; M. D,, of Mass., $30; S. R., of N. Y., $5 ; J. S , of Mass., $25. Specifications aad drawings belonging to parties with the followinff initials have been forwarded to the Patent Office during the week ending Saturday, Oct. 16: B, C. B., of N. Y.; T. M., of Mass.; J. F. J., of M". aT*W!ttJBft-f-tJ!L A, _Q Ohio r J- D. 0 , of N. Y. ; H. F. P., of N. Y.; H. L., of Mass.
This article was originally published with the title "To Correspondents"